EXTREMITY. 



167 



The direction of the canal is upwards towards 

 the head of the femur. 



The inferior extremity of the femur is much 

 more considerable than the superior. We no- 

 tice upon it two articular processes of large 

 size, united in front, but separated by a deep 

 depression posteriorly. These processes are the 

 external and internal condyles ; at the point of 

 union of these two condyles in front, *we ob- 

 serve a transversely concave surface, which ex- 

 tends for a little distance upwards upon the 

 anterior surface of the bone ; this is the trochlea 

 of the femur, on which the patella moves. The 

 deep notch which separates the condyles poste- 

 riorly is denominated the intercondyloid notch. 



Each condyle is ovoidal in its outline and 

 convex. The external condyle is placed di- 

 rectly under the external part of the femur; it 

 projects more forwards than the internal con- 

 dyle ; its antero-posterior diameter is less than 

 that of the internal condyle, but its trans- 

 verse is greater. On the other hand, the in- 

 ternal condyle projects inwards out of the 

 plane of the internal surface of the bone; 

 its posterior extremity extends much further 

 backwards than that of the external, and if 

 the bone be placed at right angles with a 

 plane surface, it will be seen that this condyle 

 alone touches that surface, a circumstance 

 which arises from the internal condyle project- 

 ing downwards more than the external. It is 

 also worthy of notice, as resulting from this 

 conformation of the internal condyle, that in 

 order to bring both condyles in contact with a 

 plane surface, the bone must be made to in- 

 cline with the inferior extremity inwards. Above 

 the posterior extremity of each condyle there is 

 a depression for the insertion of the two heads 

 of the gastrocnemius muscle. 



The external surface of the external condyle 

 is continuous with the outer surface of the 

 shaft; it is rough and convex, and is called by 

 some anatomists the external tuberosity. At its 

 posterior part there is a prominent tubercle to 

 which the external lateral ligament is attached, 

 and below and a little posterior to this is a de- 

 pression into which the tendon of the popliteus 

 is inserted. The internal surface of this con- 

 dyle forms the outer wall of the depression 

 which separates the condyles behind; it is 

 concave, and has the anterior crucial ligament 

 inserted into it. The inner wall of this notch 

 is formed by the external surface of the in- 

 ternal condyle, which is likewise concave, and 

 into it are implanted the fibres of the pos- 

 terior crucial ligament. The internal surface 

 of this condyle, or the internal tuberosity, is 

 rough, much more convex than the external 

 tuberosity; the internal lateral ligament and 

 tendon of the adductor raagnus are inserted 

 into it. Both the tuberosities are perforated 

 by a number of minute foramina for the trans- 

 mission of vessels to the cancellated texture. 



Structure. A vertical section of the femur 

 demonstrates its structure to be the same as 

 that of all the long bones, composed of can- 

 cellated texture at the extremities and com- 

 pact in the shaft, which is bored by a cylin- 

 drical canal. Posteriorly the compact tissue is 



of great density and hardness, especially wriere 

 it forms the linea aspera or spine of the bone. 

 When the section of the femur is made so as 

 to divide the neck vertically in its long axis 

 into two equal portions, we observe how ad- 

 mirably the arrangement of the osseous texture 

 in this part is adapted to the function which it 

 has to perform. The head is entirely composed 

 of reticular texture surrounded by a thin cortex ; 

 this cortex gradually increases in thickness on 

 the upper surface of the neck till it reaches the 

 great trochanter. On the inferior surface of the 

 neck, however, the compact tissue, although 

 thin near the head, becomes very much in- 

 creased in thickness as it curves downwards 

 and outwards to the lesser trochanter. We 

 observe, moreover, that although the principal 

 portion of the head and neck are composed of 

 reticular texture, in certain parts this texture is 

 more loose than in others. From the upper part 

 of the head to the thick part of the compact tissue 

 on the inferior surface of the neck, a series of 

 parallel fibres proceed in an oblique course, 

 and closely applied to one another; these fibres 

 receive and transmit the weight to the arch of 

 the neck. Again, the reticular texture is loose 

 and rare, external to these fibres and in all the 

 inferior part of the head of the bone where no 

 stress is laid upon the bone. 



Developement. According to Beclard, the 

 femur begins to ossify before the humerus ; its 

 ossification commences about the thirtieth day 

 by a point for the shaft. A second point of 

 ossification is for the inferior extremity, and 

 this consists in a single osseous nucleus which 

 is formed within the last month of fo?tal ex- 

 istence, and is situated between the two con- 

 dyles, occupying the centre of the cartilage. 

 According to Cruveilhier this osseous nucleus 

 appears during the last fifteen days of intra- 

 uterine life. " The constant presence," adds 

 this author, " of this osseous point in the inferior 

 extremity of the femur is a fact of great im- 

 portance in legal medicine ; because from the 

 knowledge of this circumstance alone, namely, 

 that this nucleus exists in the epiphysis of the 

 inferior extremity of the femur of a fetus, we 

 can pronounce that foetus to have arrived at its 

 full period." 



The neck of the femur is formed by an ex- 

 tension from the body. The head has a distinct 

 point of ossification which begins to form at 

 the end of the first year. The trochanters have 

 each a separate point of ossification ; that of 

 the great trochanter is formed about the third 

 or fourth year, that of the lesser from the thir- 

 teenth to the fourteenth year. These several 

 osseous points are united to the shaft about the 

 period of puberty in the following order; first, 

 the trochanter minor, next the head and trochan- 

 ter major, and lastly the inferior extremity. 



In the skeleton the femur is articulated so 

 that its inferior extremity approximates the 

 corresponding part of the bone of the op- 

 posite side, while the superior extremities are 

 separated from each other to a considerable 

 extent. One object of this oblique position*' 

 the femora has been already referred to, namely, 

 to bring both condyles of each femur in con- 



